Filter Strip Iowa Job Sheet

Natural Resources Conservation Service Iowa Conservation Practice 393Des Moines, Iowa June 2017

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United States Department of Agriculture

DefinitionFilter strips are an area of herbaceous vegetation that remove contaminants from overland flow.

PurposeFilter strips are established where environmentally-sensitive areas need to be protected from sediment, other suspended solids, and dissolved contaminants in runoff.

Practice InformationFilter strips are generally located at the lower edge(s) of a field and are designed to serve as a buffer between a field and environmentally-sensitive areas, such as streams, lakes, wetlands, and other areas susceptible to damage by sediment and waterborne pollutants.

In addition to serving as a buffer, filter strips can provide additional benefits, with proper plant selection and management. Additional benefits include:

» Improved fish and wildlife habitat » Improved field access » Increased livestock forage

Plans and SpecificationsSpecifications for establishment and operation of this practice will be prepared for each field or treatment unit. Record the specifications using the implementation document attached. The specifications will identify at a minimum the following:

» Practice purpose(s). » Length, width (flow length through the filter

strip), and slope of the filter strip to accomplish the planned purpose(s).

» Plant species selection and seeding/planting rates to accomplish the planned purpose(s).

» Planting dates and methods. » Specific care and handling requirements of the

seed or plant material.

» A statement that only viable, high quality, and adapted seed will be used.

» Site preparation instructions to establish and grow selected species.

Operation and MaintenanceOperate and maintain filter strips by mowing, fertilizing, controlling weeds, and reseeding (as needed) to promote dense vegetative growth. After storm events, inspect filter strips, and fill gullies and remove accumulated sediment, if needed, to keep filter strips functioning effectively. Additional operation and maintenance activities:

» Exclude livestock and vehicular traffic from filter strips during wet periods of the year to reduce compaction that will limit infiltration.

» If grazing is used to harvest vegetation, the grazing plan must ensure that the integrity and function of the filter strip is not adversely affected.

» Harvest filter strip vegetation as appropriate to encourage dense growth, maintain an upright growth habit, and remove nutrients and other contaminants that are contained in the plant tissue.

» If prescribed burning is used to manage and maintain the filter strip, an approved burn plan

Filter Strip (393) Natural Resources Conservation Service

must be developed. » Periodically re-grade and re-establish the filter

strip area when sediment deposition at the filter strip-field interface jeopardizes its function.

» Organic producers may have to maintain records for five years as part of their Organic System Plan.

Special Considerations » Filter strip width can be increased as necessary

to accommodate harvest and maintenance equipment.

» Filter strips with the leading edge on the contour will function better than those with a gradient along the leading edge.

» Seeding rates that establish a higher stem density than the normal density for a high quality grass hay crop will be more effective in trapping and treating contaminants.

Seeding Dates & RatesAll seed shall be high quality and comply with Iowa Seed and Weed Laws; and originate from the United States or Canada.

Seed rates shall be based on Pure Live Seed (PLS).

Germination tests are required for all warm and cool season grasses and legumes (excluding companion crops). Germination tests must not be older than 12 months at the time of seeding, excluding the month of testing. Inoculate legume seed before seeding with inoculant specific for the species. Re-inoculate uncoated seed if pre-inoculated more than 60 days prior to seeding.

For spring seedings, oats shall be seeded at a rate of one bushel/acre to reduce soil erosion and suppress weed competition. The oats shall be clipped prior to seed head emergence (late boot stage) to prevent further competition with the new permanent cover. Mow companion crops no later than just prior to seed head emergence the late boot stage. Do not allow companion crops to form seeds.

Treat legume seeds with a pure culture of nitrogen fixing bacteria prepared specifically for the species being seeded.

PLS = (% germination + % dormant seed) X % purity

United States Department of Agriculture

Producer: Project or Contract:

Location: County:

Farm Name: Tract Number:

Practice Purpose(s): (check all that apply)

Reduce suspended solids and associated contaminants in runoff and excess sediment in surface waters.

Reduce dissolved contaminant loadings in runoff.

Reduce suspended solids and associated contaminants in irrigation tail water.

393 - Filter Strip Implementation Requirements

Sensitive Feature Being Protected:

Provided Practice Cost Information (check box if):

Site-specific cost estimate or specifications for the producer to develop a cost estimate or obtain bids

Site Description:

Check box if using the Iowa Filter Strips Design Excel Worksheet. If so, attach it, or complete the following:

Size of area contributing sheet flow to the filter strip (Do NOT include concentrated flow acres): acres

Planned RUSLE2 on Contributing Area: tons/acre

Predominant % Slope on Contributing Area: %

Planned Ratio of contributing area to filter strip area: (watershed acres (sheet flow)/filter strip acres = ratio)

Planned Life expectancy of Filter Strip if ratio exceeds 60:1 or if predominant slope exceeds 12%: years

Description of work (include concentrated flow treatment:Include a practice location map showing detailed aerial view of where practice is to be installed on farm/site, showing all major components, stationing relative location to any landmarks, and survey benchmarks.

United States Department of Agriculture

393 - Filter Strip Implementation Requirements

Field number/location: Acres installed: Seeding date:

Average width: Minimum width: Filter strip length:

Site preparation:

Planting method:

Planting description (e.g., warm season grasses only):

Seeding rates and species (check box if):Utilizing alternate seed calculation worksheet. (Attach)

Seeding rates and species (woody species units are plants/linear ft.)

Plant species lbs./acre of seed (PLS) Total lbs. of seed for planned acreage

To figure pure live seed (PLS) rates, multiply the percent purity by the percent germination. Divide the seeding rate by the percent PLS to find the bulk seed needed per acre. For example, 98% purity x 60% germination = 0.588% PLS 10 lbs./acre x 0.588% PLS = 17 lbs./acre

Operation and Maintenance: (check all that apply)

For the purposes of filtering contaminants, permanent filter strip vegetative plantings shall be harvested as appropriate to encourage dense growth, maintain an upright growth habit, and remove nutrients and other contaminants that are contained in the plant tissue.

Control undesired weed species, especially State-listed noxious weeds.

If prescribed burning is used to manage and maintain the filter strip, an approved burn plan must be developed.

Inspect the filter strip after storm events and repair any gullies that have formed, remove unevenly deposited sediment accumulation that will disrupt sheet flow, reseed disturbed areas, and take other measures to prevent concentrated flow through the filter strip.

Apply supplemental nutrients as needed to maintain the desired species composition and stand density of the filter strip.

Periodically regrade and reestablish the filter strip area when sediment deposition at the filter strip-field interface jeopardizes its function. Reestablish the filter strip vegetation in these regraded areas, if needed.

If grazing is used to harvest vegetation from the filter strip, the grazing plan must ensure that the integrity and function of the filter strip is not adversely affected.

Certification:I certify that implementation of this conservation practice is complete according to NRCS standards and specifications and meets criteria for the stated purpose(s).

Planner/Technical Service Provider Signature Date

Landowner/Contractor Signature Date

Index

Cover Sheet

Specifications

Operation & Maintenance

Utility Safety/One-Call System Information

United States Department of Agriculture

393 - Filter Strip Implementation Requirements

Drawings